r1 = [];
r2 = [];
r3 = [];
r4 = [];

for K=linspace(0,10000,1000)
  r1 = [r1 findRootLocus([K], [1 18 80 0])'];
  r2 = [r2 findRootLocus([K], [1 3 4 2])'];
  r4 = [r4 findRootLocus([K 4*K 8*K], [1 0 0 7])'];
end

for K=linspace(0,10000,2000)
  r3 = [r3 findRootLocus([K 5], [1 9 14 0])'];
end

subplot(2,2,1)
plot(r1, '.');

subplot(2,2,2)
plot(r2, '.');

subplot(2,2,3)
plot(r3, '.');

subplot(2,2,4)
plot(r4, '.');
